Then I recently read the second edition of J. Shep Jeffreys' book HELPING GRIEVING PEOPLE -- WHEN TEARS ARE NOT ENOUGH: A HANDBOOK FOR CARE PROVIDERS (2011), mentioned above. In my case I am not trying to be a care provider for anybody else but myself.
Jeffreys ably covers certain works in the professional literature that I had read as well as other works that I had not read. In the spirit of giving credit where credit is due, he surveys the professional literature and summarizes what each author says -- without trying to adjudicate competing claims made by different authors. But his own contribution is in the overall editorial apparatus that he uses in organizing the book and in the direct editorializing that he occasionally provides as he proceeds, most notably on pages 46-49.
As Jeffreys explains, attachment theory as advanced by John Bowlby and others dominates the professional literature about loss and mourning. Briefly stated, we form attachments, which are also referred to as attachment bonding and attachment bonds. We feel a sense of loss in our lives when we experience the loss of an attachment bond with someone or something (including the loss of our dreams in which we had invested ourselves).
In other words, no attachment bond = no experience of loss = no experience of mourning a loss.
As Jeffreys indicates, there are two broad categories of loss:
(1) loss due to the death of someone significant in our lives, which is also known as bereavement, and
(2) nondeath losses.
When we speak of the death of a loved one, we usually think of the death of a marital partner or a romantic lover or a family member, where we have established a personal two-way love relationship with another individual person. However, I would note that presidential candidates in the United States try to win our votes and approval. In a sense, they try to win our love.